Selective cleavage of the heregulin receptor ErbB-4 by protein kinase C activation

Manuela Vecchi, Josep Baulida, Graham Carpenter

Research output: Contribution to journalArticlepeer-review


The 180-kDa transmembrane tyrosine kinase ErbB-4 is a receptor for the growth factor heregulin. 125I-Heregulin binding to NIH 3T3 cells overexpressing the ErbB-4 receptor is rapidly decreased by 12-O- tetradecanoylphorbol-13-acetate (TPA) pretreatment. Immunologic analysis demonstrates that TPA treatment of cells induces the proteolytic cleavage of ErbB-4, producing an 80-kDa cytoplasmic domain fragment, which contains a low level of phosphotyrosine, and a 120-kDa ectodomain fragment, which is released into the extracellular medium. Cleavage of ErbB-4 was also enhanced by other protein kinase C activators, i.e. platelet-derived growth factor, ionomycin, and synthetic diacylglycerol, while protein kinase C inhibition or down-regulation suppressed the TPA stimulation of ErbB-4 degradation. TPA did not induce the degradation of related receptors (ErbB-1, ErbB-2, and ErbB-3) in the EGF receptor family. The phorbol ester-induced cleavage of ErbB-4 occurs within or close to the ectodomain, as the 80-kDa cytoplasmic domain fragment is recognized by antibody to the ErbB-4 carboxyl terminus and is membrane-associated. Coprecipitation experiments show that, while the 80-kDa ErbB-4 fragment is associated with the SH2-containing molecules PLC-γ1 and Shc, TPA did not induce the phosphorylation of these substrates in intact cells. In addition, kinase assays in vitro indicate that the 80-kDa fragment is not an active tyrosine kinase. These results show that protein kinase C negatively regulates heregulin signaling through the ErbB-4 receptor by the activation of a selective proteolytic mechanism.

Original languageEnglish
Pages (from-to)18989-18995
Number of pages7
JournalJournal of Biological Chemistry
Issue number31
Publication statusPublished - 1996

ASJC Scopus subject areas

  • Biochemistry


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